Rotary converter.



J. B. BASSETT.

ROTARY CONVERTER.

APPLICATION man APR.19.1915. RENEwED Aus. 12,1916.

Patented Nov. 1'3, 1917.

Inventor t! @www s n S T a /Lw B t B+ n. A m H O J um |D UNITED sTATEs PATENT oEErcE.

JOHN B. BASSETT, OF SCHENCTADY, NEW YORK, ASSIG-NOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ROTARY CONVERTER Specication of Letters Patent.

Patented Nov. 13, 191 '7.

Application led April 19, 1915, Serial No. 22,293. Renewed .August 12, 1916. Serial No. 114,642.

To all whom it may concern: l

Be it known that I, `J0HN B. BAssE'r'r, a citizen of the United States, residin at Schenectady, county of Schenectady, tate of New York, have invented certain newv verter when boosting and a generator loadl on the converter when bucking; or, in other words, when the booster is boosting the voltage of the converter it must be driven asa generator by the converter, but when operating to buck the converter voltage the booster operates as a motor transmitting mechanical energy to the converter. Under such conditions, the effective' armature reaction of the rotary converter varies through wide limits and directly aieots the magnetization of the commutating poles. The armature reaction caused by the booster when boosting the converter voltage is in a direction to a'dd to the excitation of the commutating poles of theconverter, whereas under the bucking condition the armature reactionfcaused by the booster is in a direction to subtract from the excitation of the commutating poles of the converter.

My invention provides a novel and simplel exciting system and a novel method for automatically adjustin the strength of the commutating eld o a. booster t pe rotary converter to the correct value un er-all consponsive means'is preferably so constructof which the following is aspeciprovided lwith coils energized by the current and :voltage of the booster and a balancing element provided with a coil energized by the current iiowing in the commutating field winding which is connected to the above mentioned source of voltage. With such an arrangement, since the armature reaction of the'converter depends upon the motor or generator load of the booster, that is upon the booster watts, and also upon the current delivered by the converter, it will be seen; that by the use of my invention the commutatingfeld strength will be automatically varied in accordance with all of these factors. y

For a better understanding of my invention reference may be had to the following description taken in connection with the accompan ing 'drawing in which the single figure s ows diagrammatically one embodilment of my invention.

In thev rawing, I have shown arotary converter 1 having a main exciting winding 2, a series commutating or interpole field winding -3 andan auxlliary commutatin field winding 4. The converter 1 is mechanlcally connected to a booster 5 having a field winding 6.v The booster is shown as being of the synchronous type connected through collector |rings 7 to alternating current mains 8 and havin its alternating current windings connecter? to the armature windings of the converter. The armature of the converter is shown as being connected to a source of exciting current comprising the direct, current mains 9 as is the auxiliary commutating field winding 4 and the booster field windingl 6. The field of the booster may be varied and reversed by connecting its field winding to a source of `voltage which may be varied over av wide range and reversed. This source of voltage comprises a set of resistances 10 connected across the direct current mains 9. The field produced by the auxiliary commutating field winding may be varied and reversed by connecting it to a source of voltage which may be varied over a Wide range and, reversed. This source of voltage also comprises a set of resistances 11 connected across the direct current mains 9. lThe sets of resistances 10 and 11 are preferably the resistance elements of double dial rheostats 12 and 13. The current supplied to the. ield winding 6 of the booster and the current supplied to the auxiliary commutating field winding 4 are therefore adjusted or regulated by means of the double dial rheostats 12 and 13.

The double dial rheostat 13 is controlled or operated by an electro-responsive ormotor means subject to the control of the energy conversion of the boostervmachine comprising a contact making wattmeter 14 through solenoids l5 and 16 and gearing 17. -.The solenoids l5 and 16 constitute the energizing coils of electro-magnets which maybe of any desired form. The contact making wattmeter comprises a wattmeterelernent The wattmeter 1 and a balancing element. element comprises two mutually interacting elements, one of which has a coil 18l energized proportionally to the current flowing through the booster and the other of which has a coil 19 energized proportionallyto the voltage of the booster, both in direction and magnitude. The voltage coil 19 is shown as connected across one phase of the booster winding and is consequently energized by the voltage in this phase, and the .current coil 18 is shown as bein connected to acurrent transformer 20 in t e same phase of the booster. The balancing element of the wattmeter comprises a coil 21 energized by the current flowing in the circuit of the auX- iliary commutating field winding 4, it being connected in the circuit of this winding. The balancingelement also has permanent magnets 22. The movable contact 37 and the stationary contacts 23 and 24 of the contact making wattmeter control the circuits of solenoids 15 and 16, which in turn control clutches 25 and 26. The gearing 171is driven by a motor 27 When one or the other of the clutches 25 or 26 is operated by one orthe other of the solenoids the gearing is connected to the shaft 28 so as to drive it in one direction or the other and consequently the double dial rheostat 13 to which the shaft 28 is mechanically connected, the motor 27 being in continuous operation and always rotating in the same direction.

The set of resistances 10 of the double dial rheostat 12 is connected to two rows of contacts 29 and 30. The terminals of the booster field 6 are connected to arms 31 and 32 of this rheostat, these arms being rigidly connected together. When these arms engage the extreme left hand co-ntacts, the full voltage of the mains is applied to this field winding in one direction. By moving the arms to adjacent contacts, a voltage less than that of the mains is applied to this field winding. A further movement of the arms toward the right still lfurther decreases the voltage applied to the winding 6. WhenV the arms engage the middle contacts, no voltage isapplied to the winding 6. A further movement of the arms toward the right applies a voltage less than the line voltage to the Winding 6 which is` in the opposite direction to that which 1was applied when the arms engaged contactsto the left of the middle. As the arms approach the extreme .right hand contacts, the voltage applied increases until they'eiigage these latter contacts, when full voltage is applied to the rows of contacts 33 `and 34, and the termi` nals vof the 4auxiliary commutating field winding 4 are connected to the arms 35 and 36, which are rigidly connected-together and engage the-rows of contacts 33 and 34. The

lvoltage applied to the field winding 4 is'varied and reversed as the. arms 35 and 36 move from left to right as explained above in connection with the booster field winding 6.v

The operation of my arrangement is as follows z- Assume now that .the arms 31, 32, 35 and 36 are in-their mid-positions, in which case no voltage is applied to either windings or 4, and consequently no current Hows in them. The booster 5 then neither bucks nor boosts and therefore .generates substantially no voltage. No current then 4flows in the Volt age coil 19 of the wattmeter element of the contact making wattmeter and therefore no torque is developed in this element. Similarly no current flows in the coil 21 of the balancing element and consequently 'die movable contact 37 of the contact making wattmeter stays in its mid position and does not close the circuit of either of the solenoids 15 or 16. If now it is desired to raise the voltage delivered by the rotary converter, the arms B17/and 32 are moved in such a dif rection that a voltage is applied to lthe field.

booster and the coil 18 is also energized, the contact 37 moving so as to close the circuit of one or theother of the solenoids `l5 or 16 through the` contact 23 yor 24,y depending upon the electrical connections, thus throwing in one or the other of the clutches 25 or 26whereupon the arms 35 and 36 begin to move as the gearing 17 is in constant motion.' A voltage is thereby applied-to the auxiliary commutating field winding 4 so that the fieldproduc'ed by it opposes the fieldl produced by the seriescommutating field -winding 3. The farms continue-to moveuntil (considering a constant load' on the con'- verter the current supplied the Winding 4 is su cient to produce a torque in the coil 21 of the balancing element equal to the torque inthe wattmeter element of thecon.- tact making wattmeter.- `This will cause the contact 37 to move andopen the circuit `of' the solenoid 15 or 16 and the arms 35 and 36 will come to rest. `If'the load on the rotary increases thegtorque of the wattmetcr element will Vagain, predominate and the solenoid which was previously energized will again be energized to increase the current iii commutating field winding 4, the arms 35 and 36 moving until abalance is again reached. If the load on the rotary, decreases, the torque ofthe balancing element will predominatek and the solenoid which was not previously energized Will. now be energizedA and'will cause-the arms35 and 36 to moveto decrease the voltage applied Ito the winding 4 until a. balance is again reached. With the windingsl arranged as shown in the drawing, the arms 35 and 36 are moved to the right of their mid position for the boost condition.

If it is desired to lower the voltage of the converter, the arms Bland 32 are moved in the opposite direction from the midV posi-' tion, in which case, the booster operatesas a motor and generates a voltagein the .opposite direction to that generated when acting as a generator. rIhe voltage applied 'to the coil 19 is now in the opposite direction and.

the contact making wattmeter closes the circuit of' the solenoid which throws the clutch .y

which moves the arms 35 and 36 soas to apply a voltage to the auxiliary commutat-A ing field winding 4 whereby the eld produced by it assists the field produced by the series commutatingL field winding. An increase of load on lthe converter increases the strength .of the auxiliary commutating field winding and a decrease in load decreases the strength of `this field in the same way. as described above in connectionwith the operation of the booster "5 as a generator.

By providing the double dial rheostat 12` with a great number of resistance elements, the amount of boost or buck may be regulated by very small steps, and b providing the double dial rheostat -13v'with' a great Shown as six phasevmachines and the lmotor 27 as a three phase machine, but it is evident that they may be of any number of phases. The coils 18 and 19 of the contact making wattmeter Vare shown as being connected to the same phase of the booster, but they may be differently connected, as for instance, one coil may be in one phase and the other in a diametrically opposite phase. Under certain conditions, the series commutating field winding may be dispensed with. The booster 5 is shown as being of the synchronous tlype but obviously it might Abe of any well nown type. I aim in the appended claims to cover all such modifications, as well as any other modifications which do not depart from the spirit and sco e of my invention.

hat I" claim as new and desire to` secure, by "Letters Patent' of the United States, is:

' Y In combination, a rotary converter hav- `ing a commutating field winding, a booster mechanically connected thereto, means for varying the field of said booster, and means responsive to the voltage and current of said pooterfor controlling said commutating el .i y 2. In combination, a rotary converter hav- Linga commutating field Winding, a booster mechanically connected thereto, means for varying and reversing the field of said `booster, and means responsive to the voltage "and ycurrent of said booster and their rela- -tive directions for controlling said commuing a commutating field winding, a booster mechanically connected thereto, means for varying the field of said booster, means for varying the field produced by said commutating field Winding, and means responsive to the voltage and current of said booster for controlling said last mentioned means.

5. In combination, a rotary converter having av commutating field winding, a booster y fia-a 4. .In combination, a rotary converter havmechanically connected thereto, means for varying and reversing the field of said booster, means for varylng and reversing the field produced by said commutating field Winding, and means responsive to the voltage and current of said booster and their relative directions for controlling said last mentioned means.

6. In combination, a rotary converter having a series commutating field winding and an auxiliary commutating field Winding a booster mechanically connected to said converter, means -for varying and reversing the field of said booster, means for varying and reversing the field roduced by said auxiliary commutating eld Winding, and means responsive to the volta e and current of said booster and their relative directions for controlling said last mentionedl means.

7. In combination, direct current mains, a rotary converter having a commutating field Winding, a booster mechanically con# nected to said converter, means .for varying and `reversing the field of said booster, a set of resistances` connected across said mains, means for changing the connection of said commutating field Winding to said resistances and for reversing said field Winding, and meansresponsive to the voltage and current of said booster and their relative directions for controlling said last mentioned means.

8. In combination, direct current mains, a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a set of resistances connected across said mains, means for changing the connection of said commutating field Winding to said resistances and for reversing said field Winding, and means responsive to the voltage and current of said booster and their relative `directions for controlling said lastmentioned means, said means comprising a contact making wattmeter, solenoids controlled thereby, clutches operated by said solenoids, and gearing.

9. In combination, direct current mains, a rotary converter having a commutatingk field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial r eostat having arms and being connected across said mains, said commutating field winding being connected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said commutating field Winding, solenoids controlling vthe movement of the arms of the double dial rheostat, and a contact making Wattmeter for closing the circuits of said solenoids, said contact making wattmeter having coils energized. by the current and voltage of said booster.

10. In combination, direct current mains, a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field Winding being connected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said commutating field winding, clutches for controlling said driving means, solenoids'for operating said clutches, and a. contact making Waittmeter for closing the circuits of said solenoids, said contact making wattmeter having coils energized by the current and voltage of said booster.

11. In combination, direct' current mains,y

a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means forvarying and reversing the field of said booster, a double dial rheostat having arms and being A connected across said mains, said commutating field Winding beingconnected to said arms of the rheostat, means for driving the arms of said rheostat so as to change and reverse the voltage applied to said auxiliary commutating field Winding, clutches for controlling said driving means, solenoids for operating said clutches and a contact making Wattmeter for closing the circuits of said solenoids, said contact making wattmeter having a coil energized by the current flowing in one phase of said booster and another coil energized by the voltage generated in the same phase of. said booster.

12. In combination, direct current mains, a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across psaid mains, said commutating field Winding being connected to said arms of the rheostatfa motor ,for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation of said arms, clutches for throwing said gearing into mesh for one or the other direction of rotation, solenoids foroperating said clutches, and a contact making Wattmeterfor closing the circuits of said solenoids, said contact making Wattmeter having coils energized by the current and voltage of said booster.

13. Incombination, direct current mains, a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field Winding being connected to the arms of said rheostat, a motor for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation of said arms, clutches for throwing said gearing into mesh for one or the other direction of rotation, solenoids for operating said clutches and a contact making wattmeter for-closing the circuits of said solenoids, said contact making Wattmeter having a coil energized by the current flowing in one phase of said booster and another coil energized by the voltage generated in the same phase of said booster.

14. In combination, a rotaryy converter having a commutating field winding, a booster mechanically connected thereto, means for varying and reversing the field of said booster, means for varying and reversing the field produced by said commutating field winding, and means for controlling said last mentioned 'means comprising a contact making wattmeter having a wattmeter element and a balancing element.

15. In combination, direct current mains, a rotary converter having a commutating field winding, a -booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field Winding being connected to said armsof' the rheostat, and means for controlling said double dial rheostat comprising a contact making wattmeter, said contact making wattmeter having a wattmeter element and a balancing element.

16. In combination, directcurrent mains, a rotary converter having a commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a

double dial rheostat having arms and being connected across said mains, said commutating field Winding being connected to said arms of the rheostat, a motor for driving said arms, solenoids controlling the movement of the arms of said double dial rheostat, and a contact making wattmeter for closing the circuits of said solenoids, said contact making wattmeter comprising a wattmeter element and a balancing element.

17. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to said arms of the rheostat, a motor for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation vof said arms, clutches for throwing said gearing into mesh for one or the other direction of rotation, solenoids for operating said clutches, and a contact making wattmeter for closing the circuits of said solenoids,'said contact making wattmeter comprising a wattmeter element and a balancing element.

18. In combination, a rotary converter having a commutating field winding, a booster mechanically connected thereto, means for varying and reversing thefield of said booster, means for varying and reversing the field produced by said commutating fie d Winding, and means for controlling said last mentioned means comprisin a contact making Wattmeter having coi s energized by the current and voltage of said Ooster.

19. In combination, a rotary converter having a commutating field winding, a. booster mechanically connected thereto, means for varying and reversing the field of saidbooster, means for varyin and reversing the field produced by sai commutating field winding, and means for controlling said last mentioned means comprising a contact making wattmeter having a coil energized by the current f'lowing in one phase of said booster and another coil energized by the voltage generated in the same phase of said booster.

20. In combination, a rotary converter having a commutating field winding, a booster mechanically connected thereto, means for varying the field of said booster, means for varying the field produced by said `commutating field winding, and means for controlling said last mentioned means comprising an element having coils energized by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

21. In combination, a rotary converter having a commutating field winding, a booster mechanically connected thereto, means for varying and reversing the field of said booster,ymeans for varying and reversing the field produced by said commutating field winding, and means for controlling said last mentioned means comprising an element having coils energized by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

22. In combination, a rotary converter having a commutating field winding, a booster mechanically connected thereto, means for varying and reversing the field of said booster, means for varying and reversing the field produced by said commutating field winding, and means for controlling said last mentioned means comprising an element having a coil energized by the current flowing in one phase of said booster and another coil energized by the voltage generated in the same phase of said booster,

and a balancing element having a coil energized by the current flowing through said commutating field winding.

23. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said commutating field winding, solenoids controllin the movement of the arms of the double ial rheostat, and a contact making wattmeter for closing the circuits of said solenoids, said contact making wattmeter having coils energized by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

24. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversin the field of said booster, a double dial r eostat having arms and being connected across said mains, said commutavting field winding being connected to said arms of the rheostat, a motor for driving said arms, solenoids controlling the movement of the arms of said double dial rheostat, and a contact making wattmeter for closing the circuits of said solenoids, said contact making wattmeter comprising a wattmeter element having coils energlzed by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

25. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said commutating field winding, clutches for controlllng said driving means, solenoids for operating said clutches, and a contact making' wattmeter for closing the circuits of said solenoids, said contact making wattmeter comprising a wattmeter element having coils energized by the current and voltage of said booster, and a balancing elelnent having a coil energized by the current flowing through said comimitating field winding.

26. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said auxiliary commutating field winding, clutches for controlling said driving means, solenoids for operating said clutches, and a contact making wattmeter for closing the circuits offsaid solenoids, said contact making wattmeter comprising a wattmeter element having a coil energized by the current flowing in one phase of said booster and another coil energized by the voltage generated ir. the same phase of said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

27. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to the arms of said rheostat, a motor for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation of said arms, clutches for throwing said gearing into mesh for one or the other direction of rotation, solenoids for operating said clutches and a contact making wattmeter for closing the circuits of said solenoids, said Contact making wattmeter comprising a wattmeter element having coils energized by the current and voltage of' said booster, and a balancing element having a coil energized by the current flowing through said commutating field winding.

28. In combination, direct current mains, a rotary converter having a commutating field winding, a booster mechanically connected to said converter, means for varying and reversing the field of said booster, a double dial rheostat having arms and being connected across said mains, said commutating field winding being connected to the arms of said rheostat, a motor for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation of said arms, clutches for throwing said gearing into mesh for one or the other direction of rotation, solenoids for operating said clutches, and a contact making wattmeter for closing the circuits of said solenoids, said contact making wattmeter comprising a wattmeter element having a coil energized by the current flowing in one phase of said booster and another coil energized by the voltage generated in the same phase of said booster, and a balancing element having a cc'iil energized by the current fiovving through said commutating field Winding. i

29. In combination, direct current mains,

a rotary converter having a series commutating field winding and an auxiliary cornmutating field Winding, a booster .mechamcally connected to said converter, means `for varying 'and reversing y the field of said booster, a double dial rheostat having arms and being connected across said mains, said auxiliary commutatingfield Winding being connected to said arms of the rheostat, means yfor driving said arms so as to change and reverse the voltage applied to, saidcommutating field Winding, clutches for controlling said driving means, solenoids for operating said clutches and a contact making Wattmeter for closing the circuits of said solenoids, said contact making Wattmeter having coils energized by the current and Mvoltage of said booster.

30. In combination, direct current mains, a rotary converter having a series commutating field Winding and an auxiliary commutating field Winding, a booster mechanically connected to said converter, means for varying and reversing the field of said so booster, a double dial rheostat having arms and being connected across said mains. said auxiliary commutating field Winding being connected to said arms of the rheostat, a motor for driving said arms, gearing interposed between said motor and said rheostat for reversing the direction of rotation of` said arms, clutches for throwing said gear- `ing into mesh for one or the other direction of rotation, solenoids for operating said clutches, and a contact making Wattmeter for closing the circuits of said solenoids, said Contact making Wattmeter having coils energized by the current and voltage of said booster.` l

3l. In combination, a rotary converter having a series colnmutating field winding and an auxiliary commutating field Winding, a booster mechanically connected thereto, means for varying and reversing the field of said booster, means for varying and reversing the field produced by said auxiliary commutating field Winding, and means for controlling said last mentioned means comprising a contact making Wattmeter having coils energized by the current and voltage of said booster. n l y y 32. In combination, a rotary converter having a series commutating field Winding and an auxiliary commutating field Winding, a booster mechanically connected thereto, means for varying the field of said booster, means for varying the field produced by said auxiliary commutating field winding, and means for controlling said last mentioned means comprising an element having coils energized by the current and voltage of said booster, and a balancing element having a coil energized `by the current flowing through said auxiliary commutating field Winding.

33. In combination, a rotary converter having a series commutating field winding and an auxiliary commutating field `Winding, a booster mechanically connected thereto, means for varying and reversing the field of said booster, means for varying an-dl reversing the field produced by said auxiliary commutating field winding, and means for controlling said last mentioned means comprising an element having .coils energized by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said auxiliaryc'ommutating field Winding.

34e.k In combination, directvcurrent mains, g5 a rotary converter having a series commutating field 'Winding and an auxiliary commutating field Winding, a booster mechanically connected to said converter, means for varying and reversingthe field of said booster, 90 a double dial rheostat having arms and being connected across said mains, said auxiliary commutating field winding being con- `nected to said arms of the rheostat, means for driving said arms so as to change and reverse the voltage applied to said auxiliary commutating field Winding, solenoids controlling the movement of the arms of the double dial rheostat, and a contact making Wattmeter for closing the circuits of said 10o solenoids, said contact making wattmeter comprising a Wattmeter element havin coils energized by the current and voltage o said booster, and a balancing element having a coil energized by the current flowing through said auxiliary commutating field Winding,

35. In combination, direct current mains, a rotary converterhaving a series commutating field Winding and an auxiliary commutating field Winding, a booster mechani-` cally connected to said converter, means for varying and reversing the field of said booster, a `double `dial 'rheostat having arms and being connected across said mains, said auxiliary commutating field winding being connected to said arms ofthe rheostat, means for driving said arms so as to change and reverse the voltagevapplied to said auxiliary commutating field Winding, clutches for controll-ingr said driving means, solenoids for y operating said clutches, and a contact making Wattmeter for closing the circuits of said solenoids, said Contact making Wattmeter comprising a Wattmeter element having coils energized by the current and voltage of said booster, and a balancing element having a coil energized by the current flowing through said auxiliary commutating field winding.

for driving said arms, gearing interposedv between said motor and said rheostatfor re-I versing the direction of rotation of said arms, clutches for throwing said vgearing into mesh for one or the other direction of rotation, solenoids for operating said clutches, and a contact making wattmeter for closing the circuits of said solenoids, said contact making wattmeter comprisin a wattmeter element having coils energize by the current and voltage of said booster,

and a -balancing element having a coil ener-l gized by the current flowing through sa-id auxiliary commutating field winding. l

37. In a booster interpolerotary converter system, the combination with an interpole field winding, of a source of exciting current connected thereto, means for regulat- Hsystem, the combination with an interpolev ing the current supplied to said field winding from said source, motor means for operating said regulating means, said motorl means comprislng two mutually interacting siem-ents, one of which is energized proportionally to the booster current and the other of which is energized'proportionally to thel booster voltage. i 4

. 38. Ina booster interpole rotary converter field winding, of a sourceA of exciting current connected thereto, means for regulating y `the current supplied to said fieldw-inding from said source,-motor means for operating said regulating' means, said motor means comprising two mutually interacting elements, one of which is energized proportion- .ally to the booster current and the other nof which is energized proportionally to the. booster voltage, both in direction andv in magnitude.

39. In a booster interpolerotary converter system, the combination'with an interpole field winding, of a source of exciting current connected thereto, meansl for re ulating thev current supplied to said field' wlnding from said source, a wattmeter mechanism coupled to adjust said regulating means, "means for energizing the voltage winding of said wattmeter mechanism proportionally to the boos- Y ter voltage, and means for energizing the current winding of said wattmeter mechanism proportionally to the booster current.

40. In a booster interpole rotaryv converter my hand this 17th system, the combination with an interpole field winding, of a source ofexciting current connected thereto, means for re iating the current supplied to said field winding from said source, a wattmeter mechanism coupled to adjust said regulating means, means for energizin the voltage winding of said watt# meter mec anism proportiona y to the boosvter voltage both in direction and magnitude,

and means'forenergizing the current windin of said wattmeter mechanism proper-j tionally tothe booster current.

41. The method of energizing the inten pole field winding of aninterpole-type booster rotary converter which comprises supplying thereto two magnetizing components, one o which varies directly with the rotary converter load current "and the other of which varies directly withthe energy electrically interchanged between the booster machine and the supply circuit.

42. In an excitin system for the'commutating field poles o a booster type interpole rotary converter, the combination with at least one of the commutating field windings, of a source of excitin from saidy source to said field winding, electro-responsive `means subject lto the control of the energy conversion of the booster machine, and means subject to the control of said electro-responsive means for adjusting the exciting current supplied to said commutating eld winding.

current, connections j 43. In an excltm system for the commutatingfield poles o a booster type interpole rotary converter, the combination with at v'least one` of the commutating field windings', of motor meansl responsive to the actual electric'al energy transferred between the supplysystem and the booster machine, and

means subject to the control of said motory means for adjusting `the exciting current supplied to said commutating field winding.

44. In an exciting system for commutat-v ing field poles of a booster type interpole `.rotary converter, the combination with at least one .of the commutating field windings, of a source ofA exciting current, connections from said source to said field winding, motor means responsive to the actual electrical energy transferredv between-the supply system and the booster machine, and means subject tothe control 'of said motor means for adjustingl the exciting current supplied to said commutating field winding, both in direction and magnitude. v

In testimony whereof, I have hereunto set day of April, 1915. JOHN B. BASSETT.

Witnesses: v f

BENJAMIN B. HULL, HELEN ORFORD.

lll 

